It's often said in the peasant villages and simple homesteads of Swabia that every church has its Angel and every castle has its Grim. Domus Cygna would seem to be typical in that respect, if in no other.
It's unknown exactly when the creature called "Himself" first appeared on the Island of Swans, who invited him, or why he stays, but he's been a resident of the castle's underground spaces since the first cellar was constructed in Caius Trajan's day.

Though it was once a favorite rite of passage among the covenant's apprentices to go in search of Himself, there is no record of anyone having seen the creature. Most often the only indication of his presence is pulled hair, the sound of clawed footsteps, and a raspy "No good, no good! Not fast enough!". Occasionally someone walking around the castle or courtyard at night will report seeing a pair of shining yellow eyes or hearing the familiar sing-song voice, but for the most part Himself confines his wandering to the cellars and basements.

Like all Grims, Himself is very protective of his adopted home, and performs a variety of useful tasks... some obvious, some less so. Among his less mysterious talents, he counts himself a champion rat-catcher. Traditional wisdom says that nothing stored in the kitchen cellar will ever be infested by vermin as long as the Grim is given his due. (A bowl of milk every evening seems to be payment enough, although he's been known to take bread left to rise overnight if a lazy kitchenmaid forgets to cut a cross in it.) No complaint is ever made about these occasional thefts. If the Grim is ever denied his payment, if his work is unfairly criticised, or if he feels that he's been insulted, he can turn very nasty indeed.

The journals of Caius Darius mention an incident in the autumn of 1091 that should be taken as a warning. A new cook was hired who had an unfortunate streak of uncompromising piety where the fae were concerned. The man forbid the maids from filling the Grim's bowl, and (without consulting the steward-) asked the parish priest to Bless the cellars. Himself responded to this affront by throwing every cooking pot in the kitchen down the well, turning every drop of wine in the cellar into vinegar, and pinching the thoughtless cook black and blue every time he ventured down the stairs. When the cook stubbornly refused to appologise, and added insult to injury by littering the cellar and kitchen floors with iron filings, Himself trussed the man like a goose, stuck him on the spit, and roasted him.

The next cook was more thoughtful of his unseen helper and saw to it that the Grim was given sweet cream every night for a year, and his own tray of buns on Midwinter.